Report the positions of a body using markers

[Nithin Kurup]

Hi,

I am trying to create a vector eqn, from a fixed point A in ground , to the center of a moving body B. I would like to know if I attach a marker(fixed) to the center point of body B, can I get the relative position data from the marker in global frame during the entire simulation.

Also could you please let me know which code to use to report the position of the marker in c++.

thanks

Nithin

[Jiang Ping]

hi nithin,

I dont think marker is necessary to calculate the vector.
You can try:

Code: Select all

	SimTK::Vec3 B_com, B_cominGround;
	Model aModel("aModel");
	OpenSim::Body B_body = aModel.getBodySet().get("B_body");
        B_body.getMassCenter(B_com);
	SimTK::State s = aModel.initSystem();
	aModel.getSimbodyEngine().transformPosition(s, B_body, B_com, aModel.getGroundBody(),B_cominGround);
	
	SimTK::Vec3 PointAinGround;

	SimTK::Vec3 VectorToCalcate = B_cominGround - PointAinGround;

[Nithin Kurup]

Dear Jiang,

Thank you so much for the idea and code. I will try it out and let you know of the result.

thanks a ton.

Nithin